Salt tolerance in plants; lessons learnt from mangroves

Title : Salt tolerance in plants; lessons learnt from mangroves

Abstract:

Salinity is one of the most deleterious abiotic stress factors that affects crop yield and reduces crop productivity. Increasing soil salinity poses a threat to food security globally. Excessive accumulation of toxic ions such as Na⁺ and Cl^- in plant cells leads to osmotic imbalance as well as ion toxicity. Mangroves such as Avicennia officinalis have evolved adaptations such as ultrafiltration at the roots aided by apoplastic cell-wall barriers to thrive in saline conditions. We characterized Cytochrome P450 genes, AoCYPs from A. officinalis and their Arabidopsis orthologs AtCYPs. We show that they are involved in apoplastic barrier formation and are induced within 30 minutes of salt treatment in the roots. Heterologous expression of AoCYPs in Arabidopsis T-DNA insertional mutants and wild-type rice conferred increased NaCl tolerance to seedlings by enhancing root suberin deposition leading to reduced Na⁺ accumulation in the shoots. Histochemical staining and GC-MS/MS quantification of suberin precursors confirmed the role of CYPs in suberin biosynthesis. Using chromatin immunoprecipitation, yeast one-hybrid and luciferase assays, we identified AtWRKYs as the upstream regulator of AtCYPs in Arabidopsis. In addition, the atwrky mutants exhibited reduced suberin and salt sensitive phenotypes, which were rescued by expressing 35S::AtCYPs in atwrky mutants. This further confirms that the regulation of AtCYPs by AtWRKYs is part of the salt tolerance mechanism, and our findings can help in generating salt tolerant crop plants.

Biography:

Dr. Sivamathini Rajappa is a Postdoctoral Research Fellow at the National University of Singapore (NUS), working at the interface of plant biology and nanotechnology under the supervision of Prof. Tedrick Thomas Salim Lew. Her research focuses on developing biomimetic nanotechnology approaches to improve plant resilience to environmental stresses, particularly salinity, and to design nanoparticle-based delivery systems for plant biotechnology and biosensing applications. She obtained her Ph.D. in Biological Sciences (Plant Biology) from NUS, where her research on molecular characterization of ion transporters involved in plant salt tolerance earned her the Gold Medal for the Best PhD Thesis awarded by the International Society of Plant Molecular Biology. She previously worked as a Postdoctoral Research Fellow at Seoul National University, South Korea, studying molecular mechanisms regulating xylem development in Arabidopsis. Her research integrates molecular biology, plant physiology, abiotic stress and nanotechnology, and she has published in leading journals including two papers in Nature Communications, as well as Nanoscale, Frontiers in Plant Science, and Plant Cell Reports. She is also actively involved in mentoring students and contributing to interdisciplinary research aimed at advancing sustainable agriculture.